<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>行内元素</title>
    <style>
        /* span、a、em、b、u、i，不能设置宽高，能并排显示 */
        a,
        span {
            width: 100px;
            height: 100px;
            background-color: red;
        }
    </style>
</head>

<body>
    <span>span行内元素</span>
    <a href="#">a行内元素</a>
</body>

</html>